FIGS. 1 and 2 show the current ejector used by most dentists. It consists of a straight tube item 1 and the Prior Art tip 2P which is about 9 mm outside diameter, less than 8 mm inside diameter and 14 mm long with six very thick reinforced slit openings at the lower side and one tiny bottom hole 2 mm above the contact surface. Each of these six slit openings is 5 mm long and 1 mm wide from side view and is also opened at the bottom for about another 2 mm, an area too big to prevent soft tissue aspiration. The tip is very hard at the corner area.
The copper reinforced tube has a outer diameter about 6 mm and inner diameter of 4 mm or a inside air flow area about 12 mm square. The net air passage cross section area from the six slit openings, the bottom hole and the surrounding gaps between the tube 1 and the tip 2P is estimated at two to three times of 12 mm square. Air being sucked into the slit openings at the top 2 or 3 mm range can fill the air flow volume inside the tube without providing any interaction or suction at the bottom 1 or 2 mm range for the saliva to jump through the air and move into the tube. Fortunately, if the tip is placed at the right place, it can be pressed into the soft tissue making the saliva level at 1 to 3 mm above the hard bottom of the tip readied to be sucked into the ejector via three vertical wall reinforcements acts as the tube and tip mating stoppers. However, if the tip is loosely left inside the mouth and not pressing down against the soft tissue, as during deep cleaning, then a 1 or 2 mm rise of liquid level would NOT be sucked into the tube when the ejector tip is perpendicular to the tissue surface, and 2 to 3 mm if it is at an angle. These liquid substances would then flow toward the throat area and causes the patient to choke; regardless what the vacuum pressure level is set at the finger controlled metal handle.